A/C - Split Systems
I’m interested in hearing people’s experiences with installing split-system a/c during extensive renovation (open walls, new wiring, etc.). Costs, of course, but I’m also weighing that against interior appearance (i.e., concealed air handlers with grills of some kind versus Mitsubishi-type wall-mounted units). Orrsuz: if you see this, I would like the pictures of your setup…
I’m interested in hearing people’s experiences with installing split-system a/c during extensive renovation (open walls, new wiring, etc.). Costs, of course, but I’m also weighing that against interior appearance (i.e., concealed air handlers with grills of some kind versus Mitsubishi-type wall-mounted units).
Orrsuz: if you see this, I would like the pictures of your setup as well. Please send to housereno at earthlink.net
Other input also welcome. Denton, what type system did you install?
Thanks HDL you are correct the variables play a big role. Will look up that City-Multi system you describe but will probably just bite the bullet and do full duct central A/C since our project is basically a gut job. Thanks again.
PDT,I’m an architect not a mechanical engineer so I can’t say what would be the best for your specific situation. I think you have a lot of variables you need to consider. Are you gut renovating or retrofitting an existing space? How many zones are appropriate regarding how you live and environmental conditions (i.e. south or west facing windows). I’m not sure I would rank the systems as EdKopel did. I’d agree that most ductless systems are a compromise. But with the system I installed you have enormous flexibility as well as the ability to bring in fresh outside air which is what I believe is Ed’s problem with most ductless systems in addition to the aesthetics. Mr. slim is a good makeshift solution when ductwork is not an option. City-Multi is a system that can deliver on all counts, aesthetics (concealable), fresh air, zone-ability, quietness, but it comes at a price. Regarding condensation, each indoor unit requires an insulated condensation drain pipe connected to the sanitary drain of the house (part of a proper install).
hey silvermax, I think edkopel said the least amount of words but the best advice 🙂
I would never consider a split system when the walls are open. Ducted all the way. Like someone said, see HOTD.
“It’s the zoning issue that’s making me consider other types of split-system a/c: condenser on the roof, air handlers on each floor, in closets or basement, plus ductwork and grilles, rather than big wall-mounted compressors.”
You confuse me a bit here, but with real ducted central air, you do one zone per compressor. You mount the compressors on the roof, or maybe, in the back yard. I have two floors, so two compressors.
If you have the space to hide the ductwork, use a ducted system. If you have some space to hide smaller ductwork use a high velocity systme like Spacepak or Unico. If you have no space and/or dont want to build soffits and shafts, go ductless. In that order. Ed Kopel Architects
Hey HDL, also interested in central AC/ heating and concerned about the cosmetics of the split-systems and the inevitable water condensation within the walls after installation. You mention a heat pump system is that a wall mounted device as well? What would you recommend for a 5 story gut renovation?
Thanks.
Max, you have a few options with Mitsubishi. The Mr. Slim system as you describe has those ugly wall mounted or ceiling hung units. They also have a system called City-Multi which is the big brother to the Mr. Slim. The City- Multi is capable of up to 8 zones and can use a wide variety of indoor units. These indoor units can communicate with each other to send needed cooling (or heating) capacity where its needed most. In addition to the wall and ceiling units similar to the Mr. Slim there are units designed to be concealed above ceilings either as stand alone units or ducted zones within the overall system. There are low profile units where clearance is an issue and high static units for zones where there is a lot of ductwork (high static pressure needed to overcome friction within the ducts). There are also units that can be placed within an enclosure under a window much as you would a radiator. You also have the option of a straight a/c system or going with a heat pump.
I used the heat pump system (with 5 zones) in my own 3 story gut reno, and eliminated the gas furnace forced air system that a previous renovation had installed. Since then I have noticed a savings in heating costs despite the fact that this system is electrically driven (energy star rated). Heat pumps are very efficient in the 30 to 50 degree range which is most of our winter. The heat pump is not very efficient when temps drop below 5 – 10 degrees but I’ve installed a supplemental heater on the high static unit I have serving the lower floor. I think the heater only kicked on half a dozen times last year. Total installed cost was 22K (this represents a significant discount because I am an architect specializing in multi family and occasionally have the need to specify these systems). You can probably buy a similar system for under 30K. This is a top of the line solution. It’s quiet, efficient, zoned, and out of sight. Before buying this I had a straight central a/c system with a new furnace and all new ductwork priced at 19 – 20K.
Diakin makes a competing system with similar features priced a little less but I believe Mitsubishi is of higher quality.
Thank you both. Slopenick, I assume you’re talking about Mitsubishi-type units. I would like to avoid them if I can afford to do so, though they definitely seem preferable to window units if no other choice.
Bklnite: My understanding is that central a/c can’t be zoned. Am I wrong?
It’s the zoning issue that’s making me consider other types of split-system a/c: condenser on the roof, air handlers on each floor, in closets or basement, plus ductwork and grilles, rather than big wall-mounted compressors. Unico is one such system, which I saw on a recent “green” house tour. Someone else recently inquired about SpacePak, but got no responses. I’m wondering if anyone has actual experience with these or similar systems, what they might have cost, how well they work, etc.
If anyone can shed light on this issue, I’d be grateful.
Extensive reno means you should do central AC while the walls are open and you can add ducts. Otherwise be prepared to be ridiculed for your poor choice. See HOTD.
“I hate those split unit a.c.s that hang on the wall. They look cheap and announce to all that the owner did not have enough money to install real central air…”
Posted by: Minard Lafever at December 1, 2009 1:46 PM
I have a split system, but it was not installed during an extensive renovation. The split system is the best alternative for existing houses that do not currently have air ducts/central AC. Installing air ducts in an existing house – brownstone or otherwise – is prohibitively expensive and can cause some aesthetic nightmares.
The split system avoids ducts, and instead uses an a wall mounted interior unit that cools the air using refrigerant cooled in the outside unit and pumped in. You can have multiple indoor units, and zones even. The exterior unit is small enough to mount on a wall, but big enough to look ugly once it’s there.
Split units produce a lot of cool air and use tiny amounts of electricity, but the indoor and outdoor units need to be in relatively close proximity (25 feet?) and the interior unit needs to drain somewhere since condensation forms on it when it is cold. (That lowers your humidity though, a great thing in the summer….)
As far as interior appearance, yes, the interior unit of a split system is ugly, but you can hide it up high and its way better than installing ducts everywhere.
Cost: Mine is 20K Watts and it cost about $1500 for the equipment and the same again for the install, half of which was from the electrical work (Remember, for most units you will need 220 volt power).
If I had it to do over again, I would mount it as high up in the house as possible and let the cool air flow downstairs.